Bone fixation system and methods of use

ABSTRACT

A bone fixation system comprises a first fastener configured to anchor into a first vertebrae, a second fastener configured to anchor into a second vertebrae, and a set screw to retain the second fastener to the first fastener. The first fastener includes a shaft extending along a longitudinal axis and a head. The shaft includes a first cylindrical body. The head of the first fastener includes a second cylindrical body defining a passageway having an interior surface. The passageway defines a longitudinal axis that is different than the longitudinal axis of the shaft. The first cylindrical body of the shaft and the second cylindrical body of the head are angled relative to each other. A head of the second fastener is configured to engage the interior surface of the passageway of the head of the first fastener. The set screw retains the head of the second fastener in the passageway.

PRIORITY STATEMENT AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 17/359,210, filed May 31, 2022, which is continuation applicationclaiming priority to international application PCT/US2019/067149, whichdesignates the United States, in the names of Richard G. Fessler et al.entitled “Bone Fixation System and Methods of Use;” and filed on Dec.18, 2019; which claims priority from and the benefit of the filing dateof U.S. Patent Application Ser. No. 62/787,571 in the names of RichardFessler et al entitled “Bone Fixation System and Methods of Use” andfiled on Jan. 2, 2019, both of which are hereby incorporated byreference, in entirety, for all purposes.

FIELD OF INVENTION

The present invention relates generally to general surgery, orthopedicand neurosurgical implants used for insertion within a patient'svertebrae. More specifically, but not exclusively, the present inventionconcerns bone fixation systems for implantation into a patent's spine tomaintain or re-establish proper spacing and alignment of the spine.

BACKGROUND OF THE INVENTION

Spinal deformities may result from disease, age or trauma causingdestabilization of the spine. To correct destabilization of a patent'sspine, posterior fusion device systems may be used. The posterior fusiondevice systems that are currently available are designed to beapplicable to single and multiple level stabilizations using a rodextending between adjacent bone screws for strength. These posteriorfusion device systems and the instrumentation used for insertion into apatient's spine are extensive, complicated and expensive and susceptibleto loosening of the rods and screws.

SUMMARY OF THE INVENTION

Aspects of the present invention provide bone fixation systems,including at a single level or multiple levels, and methods that canmaintain or re-establish anatomic spacing within a patent's spine.

According to one aspect of the present invention, provided herein is abone fixation system, including a first or primary fastener, a second orsecondary fastener, and a set screw. The first fastener includes a shaftand an enlarged head. The enlarged head extends from and is angledrelative to the shaft. The shaft including a first longitudinal axis. Aportion of the shaft of the first fastener is configured to anchor intobone. The enlarged head of the first fastener includes a passagewayhaving an interior surface. The passageway defines a second longitudinalaxis that is dangled with respect to the first longitudinal axis of theshaft. The passageway includes a first end and a second end. Theinterior surface of the passageway defining a seat. The second fastenerincludes a shaft extending along a third longitudinal axis and a head. Aportion of the shaft of the second fastener is configured to anchor intobone. The head of the second fastener is configured to engage the seatof the first fastener. The engagement of the seat and the head allowsfor a plurality of angular relationships between the second longitudinalaxis relative to the third longitudinal axis. At least a portion of theset screw configured to secure within the passageway of the firstfastener. The set screw including a bottom surface that contacts andretains the head of the second fastener against the seat.

In another aspect, the head of the first fastener and a portion of thesecond fastener are adapted for residing outside bone.

These and other objects, features and advantages of this invention willbecome apparent from the following detailed description of the variousaspects and principles of the invention taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention and,together with the detailed description herein, serve to explain theprinciples of the invention. The drawings are only for purposes ofillustrating examples and are not to be construed as limiting theinvention. It is emphasized that, in accordance with the standardpractice in the industry, various features are not drawn to scale. Infact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 illustrates a side view of one embodiment of a bone fixationsystem, in accordance with one or more aspects of the present invention;

FIG. 2 illustrates a cross-sectional view of the bone fixation system ofFIG. 1 , in accordance with one or more aspects of the presentinvention;

FIG. 3 illustrates a partial cross-sectional view of the bone fixationsystem of FIG. 1 , in accordance with one or more aspects of the presentinvention;

FIG. 4A illustrates a prospective view of one embodiment of a firstfastener of the bone fixation system of FIG. 1 , in accordance with oneor more aspects of the present invention;

FIG. 4B illustrates a partial cross-sectional view of the first fastenerof FIG. 4A, in accordance with one or more aspects of the presentinvention;

FIG. 4C illustrates a side view of the first fastener of FIG. 4A, inaccordance with one or more aspects of the present invention;

FIG. 4D illustrates a top view of the first fastener of FIG. 4A, inaccordance with one or more aspects of the present invention;

FIG. 4E illustrates a bottom view of the first fastener of FIG. 4A, inaccordance with one or more aspects of the present invention;

FIG. 5A illustrates a perspective view of one embodiment of a secondfastener of the bone fixation system of FIG. 1 , in accordance with oneor more aspects of the present invention;

FIG. 5B illustrates a side view of the second fastener of FIG. 5A, inaccordance with one or more aspects of the present invention;

FIG. 5C illustrates a top view of the second fastener of FIG. 5A, inaccordance with one or more aspects of the present invention;

FIG. 5D illustrates a bottom view of the second fastener of FIG. 5A, inaccordance with one or more aspects of the present invention;

FIG. 5E illustrates a cross-sectional view of the second fastener ofFIG. 5A, in accordance with one or more aspects of the presentinvention;

FIG. 6 illustrates a prospective view of one embodiment of a drill guidefor use with the bone fixation system of FIG. 1 , in accordance with oneor more aspects of the present invention;

FIG. 7 illustrates a partial cross-sectional view of the drill guide ofFIG. 6 inserted into the first fastener of FIG. 4A, in accordance withone or more aspects of the present invention;

FIG. 8A illustrates a perspective view of one embodiment of a drillguide for use with the bone fixation system of FIG. 1 , in accordancewith one or more aspects of the present invention;

FIG. 8B illustrates a cross-sectional view of the drill guide of FIG.8A, in accordance with one or more aspects of the present invention;

FIG. 8C illustrates a side view of the drill guide of FIG. 8A, inaccordance with one or more aspects of the present invention;

FIG. 8D illustrates an end view of the drill guide of FIG. 8A, inaccordance with one or more aspects of the present invention;

FIG. 8E illustrates an opposing end view of the drill guide of FIG. 8A,in accordance with one or more aspects of the present invention;

FIG. 9 illustrates a side view of another embodiment of a bone fixationsystem, in accordance with one or more aspects of the present invention;

FIG. 10 illustrates a partial cross-sectional view of the bone fixationsystem of FIG. 9 , in accordance with one or more aspects of the presentinvention;

FIG. 11A illustrates a perspective view of one embodiment of a firstfastener of the bone fixation system of FIG. 9 , in accordance with oneor more aspects of the present invention;

FIG. 11B illustrates a partial cross-sectional view of the firstfastener of FIG. 11A, in accordance with one or more aspects of thepresent invention;

FIG. 11C illustrates a side view of the first fastener of FIG. 11A, inaccordance with one or more aspects of the present invention;

FIG. 11D illustrates a top view of the first fastener of FIG. 11A, inaccordance with one or more aspects of the present invention;

FIG. 11E illustrates a bottom view of the first fastener of FIG. 11A, inaccordance with one or more aspects of the present invention;

FIG. 12A illustrates a side view of one embodiment of a second fastenerof the bone fixation system of FIG. 9 , in accordance with one or moreaspects of the present invention;

FIG. 12B illustrates a cross-sectional view of the second fastener ofFIG. 12A, in accordance with one or more aspects of the presentinvention;

FIG. 12C illustrates a top view of the second fastener of FIG. 12A, inaccordance with one or more aspects of the present invention;

FIG. 13A illustrates a perspective view of one embodiment of a set screwof the bone fixation system of FIG. 9 , in accordance with one or moreaspects of the present invention;

FIG. 13B illustrates a side view of the set screw of FIG. 13A, inaccordance with one or more aspects of the present invention;

FIG. 13C illustrates a top view of the set screw of FIG. 13A, inaccordance with one or more aspects of the present invention;

FIG. 13D illustrates a bottom view of the set screw of FIG. 13A, inaccordance with one or more aspects of the present invention;

FIG. 14 illustrates an exploded side view of another embodiment of abone fixation system, in accordance with one or more aspects of thepresent invention;

FIG. 15 illustrates a cross-sectional view of the bone fixation systemof FIG. 14 , in accordance with one or more aspects of the presentinvention;

FIG. 16A illustrates a partial cross-sectional view of the bone fixationsystem of FIG. 14 , in accordance with one or more aspects of thepresent invention;

FIG. 16B illustrates another partial cross-sectional view of the bonefixation system of FIG. 14 , in accordance with one or more aspects ofthe present invention;

FIG. 17A illustrates a side view of one embodiment of a first fastenerof the bone fixation system of FIG. 14 , in accordance with one or moreaspects of the present invention;

FIG. 17B illustrates a cross-sectional view of the first fastener ofFIG. 17A, in accordance with one or more aspects of the presentinvention;

FIG. 17C illustrates a top view of the first fastener of FIG. 17A, inaccordance with one or more aspects of the present invention;

FIG. 17D illustrates a bottom view of the first fastener of FIG. 17A, inaccordance with one or more aspects of the present invention;

FIG. 18A illustrates a perspective view of one embodiment of a secondfastener of the bone fixation system of FIG. 14 , in accordance with oneor more aspects of the present invention;

FIG. 18B illustrates a side view of the second fastener of FIG. 18A, inaccordance with one or more aspects of the present invention;

FIG. 18C illustrates a top view of the second fastener of FIG. 18A, inaccordance with one or more aspects of the present invention;

FIG. 18D illustrates a bottom view of the second fastener of FIG. 18A,in accordance with one or more aspects of the present invention;

FIG. 19A illustrates a perspective view of one embodiment of a set screwof the bone fixation system of FIG. 14 , in accordance with one or moreaspects of the present invention;

FIG. 19B illustrates a side view of the set screw of FIG. 19A, inaccordance with one or more aspects of the present invention;

FIG. 19C illustrates a top view of the set screw of FIG. 19A, inaccordance with one or more aspects of the present invention;

FIG. 19D illustrates a bottom view of the set screw of FIG. 19A, inaccordance with one or more aspects of the present invention;

FIG. 20 illustrates a perspective view of one embodiment of a drillguide for use with the bone fixation system of FIG. 14 , in accordancewith one or more aspects of the present invention;

FIG. 21 illustrates a partial cross-sectional view of the embodiment ofthe drill guide of FIG. 20 for use with the bone fixation system of FIG.14 , in accordance with one or more aspects of the present invention;

FIG. 22A illustrates a side view of the drill guide FIG. 20 , inaccordance with one or more aspects of the present invention;

FIG. 22B illustrates a top view of the drill guide of FIG. 20 , inaccordance with one or more aspects of the present invention;

FIG. 22C illustrates a bottom view of the drill guide of FIG. 20 , inaccordance with one or more aspects of the present invention;

FIG. 22D illustrates a cross-sectional view of the drill guide of FIG.20 , in accordance with one or more aspects of the present invention;

FIG. 23 illustrates a perspective view of another embodiment of a bonefixation system, in accordance with one or more aspects of the presentinvention;

FIG. 24 illustrates a partial perspective view of the bone fixationsystem shown in FIG. 23 , in accordance with one or more aspects of thepresent invention;

FIG. 25 illustrates an exploded view of the bone fixation system shownin FIG. 23 , in accordance with one or more aspects of the presentinvention;

FIG. 26A illustrates one perspective view of one embodiment of a headfor use with the bone fixation system of FIG. 23 , in accordance withone or more aspects of the present invention;

FIG. 26B illustrates a side view of the head shown of FIG. 26A, inaccordance with one or more aspects of the present invention;

FIG. 26C illustrates another perspective view of the head shown of FIG.26A, in accordance with one or more aspects of the present invention;

FIG. 26D illustrates a cross-sectional view of the head shown of FIG.26A, in accordance with one or more aspects of the present invention;

FIG. 27A illustrates a perspective view of one embodiment of a firstfastener of the bone fixation system of FIG. 23 , in accordance with oneor more aspects of the present invention;

FIG. 27B illustrates a side view of the first fastener of FIG. 27A, inaccordance with one or more aspects of the present invention;

FIG. 27C illustrates a top view of the first fastener of FIG. 27A, inaccordance with one or more aspects of the present invention;

FIG. 27D illustrates a bottom view of the first fastener of FIG. 27A, inaccordance with one or more aspects of the present invention;

FIG. 28A illustrates a side view of one embodiment of a second fastenerof the bone fixation system of FIG. 23 , in accordance with one or moreaspects of the present invention;

FIG. 28B illustrates a top view of the second fastener of FIG. 28A, inaccordance with one or more aspects of the present invention;

FIG. 28C illustrates a bottom view of the second fastener of FIG. 28A,in accordance with one or more aspects of the present invention;

FIG. 29A illustrates a perspective view of one embodiment of a spacer ofthe bone fixation system of FIGS. 23-25 , in accordance with one or moreaspects of the present invention;

FIG. 29B illustrates a side view of the spacer of FIG. 29A, inaccordance with one or more aspects of the present invention;

FIG. 29C illustrates a top view of the spacer of FIG. 29A, in accordancewith one or more aspects of the present invention;

FIG. 29D illustrates a bottom view of the spacer of FIG. 29A, inaccordance with one or more aspects of the present invention;

FIG. 30A illustrates a perspective view of one embodiment of a set screwof the bone fixation system of FIG. 23-25 , in accordance with one ormore aspects of the present invention;

FIG. 30B illustrates a side view of the set screw of FIG. 30A, inaccordance with one or more aspects of the present invention;

FIG. 30C illustrates a top view of the set screw of FIG. 30A, inaccordance with one or more aspects of the present invention; and

FIG. 30D illustrates a bottom view of the set screw of FIG. 30A, inaccordance with one or more aspects of the present invention.

DETAILED DESCRIPTION FOR CARRYING OUT THE INVENTION

Generally stated, disclosed herein are different embodiments andexamples of a bone fixation system. The embodiments and examplesdescribed herein of a bone fixation system constructed in accordancewith one or more aspects of the present invention avoid the need forusing a rod to connect adjacent pedicle screws typically used in backsurgery. Without use of a connecting rod, there are less parts involvedand less movable parts and less chance of movement of the fusion systemor loosening of its components after surgery with a bone fixation systemconstructed in accordance with one or more principles or aspects of thepresent invention. A bone fixation system constructed in accordance withone or more principles or aspects of the present invention also does notrely on a connecting rod for strength. Further, surgical methods forinserting the bone fixation systems are discussed.

In this detailed description and the following claims, the wordsproximal, distal, anterior, posterior, medial, lateral, superior,inferior, cephalad and caudally are defined by their standard usage forindicating a particular part of a bone or implant according to therelative disposition of the natural bone or directional terms ofreference. For example, “proximal” means the portion of an implantnearest the insertion instrument, while “distal” indicates the portionof the implant farthest from the insertion instrument. As fordirectional terms, “anterior” is a direction towards the front side ofthe body, “posterior” means a direction towards the back side of thebody, “medial” means towards the midline of the body, “lateral” is adirection towards the sides or away from the midline of the body,“superior” means a direction above and “inferior” means a directionbelow another object or structure, “cephalad” means a direction towardthe head and “caudally” means a direction toward the inferior part ofthe body.

In general, the embodiments and examples described herein of a bonefixation system constructed in accordance with one or more principles oraspects of the present invention include a primary screw or fastener anda secondary screw or fastener. The primary fastener or fastener includesa shaft and a head angled relative to the shaft. In one example, thesecondary fastener is directly coupled to the primary fastener by, forexample, mating threads or an interference fit. In alternativeembodiments, a set screw is used to retain the second fastener withinthe head of the primary fastener. In other examples, the head of theprimary fastener provides a seat for the second fastener to enablevariable angulations of the secondary fastener relative to the primaryfastener.

In general, the head of the primary fastener is shaped and angledrelative to the shaft to enable insertion of the secondary fastenerthrough it and into an adjacent pedicle, thereby eliminating the needfor a rod or plate. The shape of the head of the primary fastenerprovides a low profile and less trauma to soft tissues when inserted,for example, via minimally invasive techniques. In one example, the headof the primary fastener is enlarged with respect to the shaft of theprimary fastener. For example, the cross-sectional width of the enlargedhead, taken normal to the longitudinal axis of the head, is greater thanthe cross-sectional width of the shaft, taken normal to the longitudinalaxis of the shaft. The head may include a body (e.g. cylindrical) thatis angled relative to the shaft of the primary fastener. The position ofthe head of the primary fastener ensures closest proximity of the headto bone, thereby maximizing strength of the system. The angulation ofthe head relative to the shaft of the primary fastener enablesappropriate direction of the secondary fastener to engage a secondvertebra or pedicle, thus eliminating the need for a rod or plate. Byminimizing the number of parts, the risk of failure through, forexample, loosening of set screws to tulip heads in conventional bonefixation systems is reduced.

In general, the head of the primary fastener and a portion of the secondfastener are configured to reside outside bone to allow for trajectoryof the secondary fastener to engage adjacent pedicle or use at multipleadjacent vertebrae levels. The head of the primary fastener isincorporated partially into the longitudinal axis of the shaft of theprimary fastener to minimize the overall size of the head, therebydecreasing soft tissue trauma on insertion and long-term irritation ofadjacent muscle. The angulated head of the primary fastener enables, forexample, in line insertion of a primary fastener screwdriver, andinsertion of a secondary fastener and screwdriver through the sameexternal entrance of the primary fastener during insertion.

The bone fixation system described herein may also include a tapering ora gradually increasing thickness of the shaft of the primary fastener asit approaches the head. This tapering or increased thickness at a regionof greatest stress on the primary fastener reduces failure throughfracture of the primary fastener and enhances the fastener to boneinterface thereby providing enhanced stability by increasing compressiveload.

The combination of the primary fastener and secondary fastener describedby the examples herein enables insertion of the bone fixation system viaeither an MIS or OPEN technique without the need for additionalinstrumentation. The system design relies on angulation of two fastenersrelative to each other for stability and minimizes the need foradditional instrumentation or components, such as, for example, rods andmultiple screw lengths and thicknesses. The design of the bone fixationsystem described herein combines the resistance to “pull out” impartedby the threads of the fasteners with that created by the angulation ofthe fasteners relative to each other, thereby making pull out virtuallyimpossible.

Referring to the drawings, wherein like reference numerals are used toindicate like or analogous components throughout the several views, andwith particular reference to FIGS. 1-8E, there is illustrated anexemplary embodiment of a bone fixation system 100. The bone fixationsystem 100 may include a first or primary fastener 110 for anchoringinto, for example, a first bone or vertebrae and a second or secondaryfastener 150 for anchoring into, for example, a second bone orvertebrae.

With continued reference to FIGS. 4A-4E, first fastener 110 may includea shaft 120, a head 130, and a longitudinal axis 121. Shaft 120 mayinclude a neck 112 connecting shaft 120 to the head 130 and one or morebone engagement mechanisms 122 to facilitate a gripping engagement offirst fastener 110 to bone. Shaft 120 also includes an outer surface114. In one embodiment, outer surface 114 may taper radially outwardfrom longitudinal axis 112 in the portion of neck 112 proximate head130.

In one example illustrated in FIG. 4A, shaft 120 may be, for example,threaded along its entire length, threaded along only a portion of thelength, or non-threaded. In the illustrated embodiment, the externalthread, for example, is a single lead thread that extends from a distaltip of the shaft to the proximal head portion. Other suitable boneengagement mechanisms may include, but are not limited to, one or moreannular ridges, multiple threads, dual lead threads, variable pitchedthreads, longitudinal splines or other geometries, and/or anyconventional bone engagement mechanism.

As shown in FIGS. 4A-4E, head 130 includes a cylindrical body 131. Inone embodiment, the diameter of cylindrical body 131 is greater than thediameter of shaft 120, when measured normal to their respectivelongitudinal axes. When connected to neck 112, head 130 appears like ahalo over shaft 120. Head 130 may form a receiving portion, such as, forexample, a passageway 132 having a longitudinal axis 134. Passageway 132may be in the form of, for example, a through hole or, alternatively, aslot formed between two arms. Passageway 132 defines an interior cavityor space having an inner surface 136 extending from a first end 138 to asecond end 140. In one embodiment, first end 138 and second end 140extend beyond the outer surface 114 of shaft 120. Passageway 132 may besized and configured to receive and allow pass through of at least aportion of second fastener 150 or other spinal connection element foranchoring the system 100 to, for example, a second bone or vertebrae.Passageway 132 may also be sized and configured to retain or secure atleast a portion of head 180 of second fastener 150.

In one embodiment illustrated in FIG. 4B, interior surface 136 ofpassageway 132 may include, for example, a threaded portion 142 thatextends along at least a portion of interior surface 136 from first end138. Passageway 132 may also include a seat 144 that may extend along atleast another portion of interior surface 136 towards second end 140. Inone example, seat 144 may be formed by interior surface 136 taperinginward towards longitudinal axis 134 as it approaches second end 140. Atool engagement opening 124 (see FIG. 4D) may be formed withinpassageway 132 and extending into neck 114 of shaft 120 for engagementwith, for example, a screwdriver for inserting first fastener 110 intothe bone. Tool engagement opening 124 may align with a cannulated boreextending through first fastener 110.

As illustrated in FIGS. 5A-5E, second fastener 150 may include alongitudinal axis 162, a proximal end 164, a distal end 166, a shaft170, a head 180 and a neck 168 connecting shaft 170 to head 180. Shaft170 may include one or more bone engagement mechanisms 172 to facilitatea gripping engagement of second fastener to bone. Shaft 170 may be, forexample, threaded along its entire length, threaded along only a portionof the length, or non-threaded. In the illustrated embodiment, theexternal thread is a single lead thread that extend from a distal tip ofthe shaft to the proximal head portion. Other suitable bone engagementmechanisms may include, but are not limited to, one or more annularridges, multiple threads, dual lead threads, variable pitched threads,longitudinal splines or other geometries, and/or any conventional boneengagement mechanism.

As shown in FIGS. 5A, 5C and 5E, head 180 may include a top surface 182,a first side portion 184 and a second side portion 186. Top surface 182may include a tool engagement opening extending into head 180. Firstside portion 184 may include external threads 188 extending along atleast a portion of the exterior surface of first side portion 184 fromproximal end 164. External threads 188 are configured to engage threadedportion 142 of interior surface 136 of passageway 132 of first fastener110. In one example illustrated in FIGS. 3 and 5E, second side portion186 of head 180 may include an exterior surface 190 that tapers inwardtowards longitudinal axis. The tapered exterior surface 190 isconfigured to engage and mate with seat 144 of passageway 132 and allowfirst fastener 110 to direct second fastener 150 seamlessly throughpassageway 132, while also preventing second fastener 150 from migratingentirely through passageway 132 of first fastener 110.

The system 100 may be implanted by first preparing a patient's vertebraefor insertion of the bone fixation system 100. In one example, thepreparation may be done using minimally invasive procedures. Next, asurgeon obtains a first fastener 110 and a second fastener 150. Firstfastener 110 is anchored or inserted into a desired bone such as, forexample, a first vertebrae. In one example, a surgeon drives firstfastener 110 into the first vertebrae using a screw driver engaged withtool engagement opening 124. Next, second fastener 150 is insertedthrough passageway 132 and anchored into another desired bone, such as,for example, a second or adjacent vertebrae. Second fastener 150 isinserted into passageway 132 until threads 188 of first side portion 184mate or engage threaded portion 142 on surface 136 in passageway 132 offirst fastener 110. In securing second fastener 150 to first fastener110, second fastener 150 is screwed into head 130 until tapered exteriorsurface 190 of second fastener 150 engages seat 144 in passageway 132 offirst fastener 110. In the system 100 illustrated in FIGS. 1-8E, secondfastener 150 is orientated in a fixed angled relationship relative tofirst fastener 110. This fixed angle is created by engagement of threads188 of first side portion 184 and tapered surface 190 of second sideportion threads 142 of head 180 of second fastener 150 with threadedportion 142 and seat 144 of passageway 132 of head 130 of first fastener110. When properly installed, the entire head 130 and a portion of shaft120 of first fastener 110 and/or shaft 170 of second fastener 150 arepositioned and reside outside the bone(s) in which first fastener 110and second fastener 150 are inserted. By positioning head 130 outsidethe vertebrae, bone fixation system 100 is configured to aid in thefusion of multi-levels of vertebrae.

Prior to insertion of second fastener 150 through first fastener 110 andinto a second desired bone, a drill guide may be used to pre-drill ahole in the bone. FIGS. 6-8E illustrate one embodiment of a drill guidethat may be used in system 100. As illustrated in FIG. 8A, drill guide192 may include a hollow elongated shaft 193 having a first end 194, asecond end 195, a handle portion 196 proximate second end 195 and a head198 at first end 194. Head 198 includes an exterior surface 199.Exterior surface 199 may be configured, sized and shaped to engagethreaded portion 142 and seat 144 of interior surface 136 of head 130 offirst fastener 110. As illustrated in FIG. 7 , head 198 of drill guide192 is received by and inserted into passageway 132. The engagement ofthreads on exterior surface 199 of drill guide 192 and threaded portion142 on interior surface 136 provide stability of drill guide 192 inrelation to first fastener 110 for pre-drilling the hole for secondfastener 150.

Another embodiment of a bone fixation system 200 is shown in FIGS.9-13D. Bone fixation system 200 may include a first or primary fastener210 for anchoring into, for example, a first vertebrae, a second orsecondary fastener 250 for anchoring into, for example, a secondvertebrae, and a set screw or locking cap 214.

With continued reference to FIGS. 11A-11E, first fastener 210 mayinclude a shaft 220, a head 230 and a longitudinal axis 221. Shaft 220may include a neck 212 connecting shaft 220 to the head 230. Shaft 220also includes an outer surface 214. A portion of the outer surface 214of shaft 220 may include one or more bone engagement mechanisms 222 tofacilitate a gripping engagement of first bone anchor to bone. In oneexample illustrated in FIG. 11A, shaft 220 may be, for example, threadedalong its entire length, threaded along only a portion of the length, ornon-threaded. In the illustrated embodiment, the external thread is asingle lead thread that extend from a distal tip of the shaft to theproximal head portion. Other suitable bone engagement mechanisms mayinclude, but are not limited to, one or more annular ridges, multiplethreads, dual lead threads, variable pitched threads, longitudinalsplines or other geometries, and/or any conventional bone engagementmechanism.

As shown in FIG. 11B, head 230 includes a cylindrical body 231. In oneembodiment, the diameter of cylindrical body 231 is greater than thediameter of shaft 220 extending to outer surface 214. When connected toneck 212, head 230 appears like a halo over shaft 220. Head 230 may forma receiving portion, such as, for example, a passageway 232 having alongitudinal axis 234. Passageway 232 may be in the form of, forexample, a through hole or, alternatively, a slot formed between twoarms. Passageway 232 defines an interior cavity or space having an innersurface 236 extending from a first end 238 to a second end 240. In oneembodiment, first end 238 and second end 240 extend beyond the outersurface 214 of shaft 220. Passageway 232 may be sized and configured toreceive and allow pass through of a second fastener 250 or other spinalconnection element for anchoring the system 200 to, for example, asecond bone or vertebrae. Passageway 232 is also configured to retain orsecure set screw 214 and at least a portion of head 280 of secondfastener 250.

In one embodiment illustrated in FIG. 11B, interior surface 236 ofpassageway 232 may include, for example, a threaded portion 242 thatextends along at least a portion of interior surface 236 from first end238. Passageway 232 may also include a seat 244 that may extend along atleast another portion of interior surface 236 towards second end 240. Inone example, seat 244 may be formed by interior surface 236 taperinginward towards longitudinal axis 234 as it approaches second end 240.

As illustrated in FIGS. 12A-12C, second fastener 250 may include alongitudinal axis 262, a proximal end 264, a distal end 266, a shaft270, and a head 280. Shaft 270 may include one or more bone engagementmechanisms 272 to facilitate a gripping engagement of second fastener tobone. Shaft 270 may be, for example, threaded along its entire length,threaded along only a portion of the length, or non-threaded. In theillustrated embodiment, the external thread, for example, is a singlelead thread that extends from a distal tip of the shaft to the proximalhead portion. Other suitable bone engagement mechanisms may include, butare not limited to, one or more annular ridges, multiple threads, duallead threads, variable pitched threads, longitudinal splines or othergeometries, and/or any conventional bone engagement mechanism.

As shown in FIG. 12A, head 280 may include a top surface 282 and a sideportion 284. Top surface 282 may include a tool engagement opening (seeFIG. 12C) extending into head 280. Side portion 284 of head 280 mayinclude an exterior surface 290 that tapers inward towards longitudinalaxis 262. The tapered exterior surface 290 is configured to engage andmate with seat 244 of passageway 232.

As shown in FIGS. 13A-13D, set screw 214 may include a top surface 215,side surface 217 and a bottom surface 219. Set screw 214 may alsoinclude a tool engagement opening 216 extending into set screw 214 fromtop surface 215 toward bottom surface 219. In addition, set screw 214may include threads 218 on side surface 217 extending, for example, fromtop surface 215 to bottom surface 219, or along a portion thereof.Bottom surface 219 may be sized and shaped to engage at least a portionof head 280 of second fastener 250.

The system 200 may be implanted by first preparing a patient's vertebraefor insertion of the bone fixation system 200. Next, the first fastener210 is screwed or inserted into the bone, e.g. vertebrae. In insertingfirst fastener 210 into the bone, a surgeon may use a screw driver thatengages a tool engagement opening 235 (see FIG. 11D) formed withinpassageway 230. Next, second fastener 250 is inserted through head 230of first fastener 210 and into a second desired bone until exteriortapered surface 290 engages seat 244 of passageway 232 of head 230 offirst fastener 210. When properly installed, the entire head 230 and aportion of shaft 120 of first fastener 210 and/or shaft 270 of secondfastener 250 are positioned and reside outside the bone(s) in whichfirst fastener 210 and second fastener 250 are inserted. By positioninghead 230 outside the vertebrae, bone fixation system 200 is configuredto aid in the fusion of multi-levels of vertebrae.

Prior to insertion of second fastener 250 into first fastener 210, drillguide 192 may be used to pre-drill a hole in the bone. Next, set screw214 may be inserted or screwed into passageway 232 to secure secondfastener 250 in the desired position. Finally, the patient's incisionmay be closed. In the system 210 illustrated in FIGS. 9-13D, secondfastener 250 is orientated in a fixed angled relationship relative tofirst fastener 210. This fixed angle is created by engagement of taperedsurface 290 of side portion 284 of head 280 of second fastener 250 withseat 244 of passageway 232 of first fastener 210.

Another embodiment of a bone fixation system 300 is shown in FIGS.14-22D. Bone fixation system 300 may include a first or primary fastener310 for anchoring into, for example, a first vertebrae, a second orsecond fastener 350 for anchoring into, for example, a second vertebrae,and a set screw or locking cap 314. In one example, first fastener 310may be cannulated with a threaded halo head, second fastener 350 may becannulated with an articulating spherical head, and set screw 314 may becannulated and include a bottom surface for capturing and securing thespherical head of second fastener 350.

As shown in FIGS. 17A-17D, first fastener 310 may include a cannulatedshaft 320, a head 330 and a longitudinal axis 321. Shaft 320 may includea neck 312 connecting shaft 320 to the head 330 and an outer surface313. In one example, as illustrated in FIGS. 17A and 17B, a portion ofouter surface 313 of neck 312 may taper radially outward relative tolongitudinal axis 321 to provide additional thickness to neck 312 ofshaft 320 as it approaches head 330. This taper or increased thicknessprovides, for example, enhancement of the fastener to bone interfacethereby providing enhanced stability by increasing compressive load andreduces failure through facture of the fastener.

A portion of outer surface 313 of shaft 320 may include one or more boneengagement mechanisms 322 to facilitate a gripping engagement of firstbone anchor to bone. In one example illustrated in FIG. 17A, shaft 320may be, for example, threaded along its entire length, threaded alongonly a portion of the length, or non-threaded. In the illustratedembodiment, the external threads, for example, may be a single leadthread that extend from a distal tip of the shaft to the proximal headportion. Other suitable bone engagement mechanisms may include, but arenot limited to, one or more annular ridges, multiple threads, dual leadthreads, variable pitched threads, longitudinal splines or othergeometries, and/or any conventional bone engagement mechanism.

As illustrated in FIG. 17B, head 330 includes a cylindrical body 331. Inone embodiment, the diameter of cylindrical body 331 is greater than thediameter of shaft 320 extending to outer surface 313. Head 330 may forma receiving portion, such as, for example, a passageway 332 having alongitudinal axis 334. Passageway 332 may be in the form of, forexample, a through hole or, alternatively, a slot formed between twoarms. Passageway 332 defines an interior cavity or space having an innersurface 336 extending from a first end 338 to a second end 340. In oneembodiment, first end 338 and second end 340 extend beyond the outersurface 313 of shaft 320. Passageway 332 may be sized and configured toreceive and allow pass through of a second fastener 350 or other spinalconnection element for anchoring the system 300 to, for example, asecond bone or vertebrae. Passageway 332 is also configured to retain orsecure set screw 314 and at least a portion of head 380 of secondfastener 350.

In one embodiment illustrated in FIG. 17B, interior surface 336 ofpassageway 323 may include, for example, a threaded portion 342 thatextends along at least a portion of interior surface 336 from first end338. Passageway 332 may also include a seat 344 that may extend along atleast another portion of interior surface 336 towards second end 340. Inone example, seat 344 may be shaped to correspond and mate with theshape of a portion of head 380 of second fastener 350.

Passageway 332 is in communication with the cannulated tube orpassageway extending through shaft 320 of first fastener 310. In oneexample, passageway 323 and the cannulated tube or passageway extendingthrough shaft 320 are configured to receive a K-wire to assist ininserting first fastener 310 into the bone or vertebrae at a properlocation and position. A tool engagement opening 324 such as, forexample, a cannulated hex receiver hole, is formed in interior surface336 and into shaft 320 between passageway 323 and the cannulated tube326. Tool engagement opening 324 receives a hex driver or screwdriverand assists in inserting or screwing first fastener 310 into the bone.

As illustrated in FIGS. 18A-18D, second fastener 350 may include alongitudinal axis 362, a proximal end 364, a distal end 366, acannulated shaft 370, a head 380 and a neck 368 connecting shaft 370 tohead 380. The outer surface of shaft 370 may include one or more boneengagement mechanisms 372 to facilitate a gripping engagement of secondfastener to bone. Shaft 370 may be, for example, threaded along itsentire length, threaded along only a portion of the length, ornon-threaded. In the illustrated embodiment, the external thread is asingle lead thread that extend from a distal tip of the shaft to theproximal head portion. Other suitable bone engagement mechanisms mayinclude, but are not limited to, one or more annular ridges, multiplethreads, dual lead threads, variable pitched threads, longitudinalsplines or other geometries, and/or any conventional bone engagementmechanism.

As illustrated in FIG. 18A, head 380 may include a top surface 382 and aside portion 384. Top surface 382 may include a tool engagement opening383 extending into head 380. Side portion 384 of head 380 may include anexterior surface 390 shaped like, for example, a polyaxial screw head inthe form of, for example, a bulbous head, hemispherical, or partiallyspherical head. Exterior surface 390 may be shaped to lie in or matewith seat 344 formed in interior surface 336 of passageway 332 of head330 of first fastener 310 near second end 340. Seat 344 preferably has ashape that matches or corresponds to the shape of a portion of thepolyaxial side portion 384 and allows, for example, pivoting, spinningand rotation of second fastener 350 relative to longitudinal axis 334 ofhead 330 of first fastener 310. This configuration allows a range ofmotion along several different axes, e.g. multi-directional movement orrotation or angulation, of second fastener 350 relative to longitudinalaxis 334. For example, a round head 380 of second fastener 350 matingwith a mating concave-shaped seat 344 enables a variation of angulationto accommodate pedicle screw insertion in variable anatomy. Such a roundhead 380 transfers the variable angulation from the tulip head of atraditional pedicle screws to the secondary fastener 350.

After second fastener 350 is positioned into bone in a selecteddirection and orientation relative to first fastener 310, set screw 314,as illustrated in FIGS. 19A-19D, may lock the orientation of secondfastener 350 relative to first fastener 310. Set screw 314 may have anysuitable size, configuration and means for securing polyaxial screw head380 to seat 344 in a selected orientation relative to first fastener310. In one embodiment shown in FIGS. 19A-19D, set screw 314 may includea top surface 315, side surface 317 and a bottom surface 319. Set screw314 may also include a tool engagement opening 316 extending into setscrew 314 from top surface 315 toward bottom surface 319. In oneexample, set screw 314 may be cannulated, but in other examples may not.In addition, set screw 314 may include threads 318 on side surface 317extending, for example, from top surface 315 to bottom surface 319, oralong a portion thereof. As shown in FIGS. 16A and 16B, bottom surface319 is sized and shaped to retain head 380 with the aid of seat 344.

The concave contour of bottom surface 319 of set screw 380 is configuredto match or correspond to head 380 of second fastener 350 in order to,for example, maximize surface contact and, therefore, maximize therigidity of the system. In one embodiment, bottom surface 219 mayinclude a surface treatment, such as, for example, surface etching,which engages and/or interacts with head 380 of second fastener 350 toprovide, for example, enhanced rigidity through a friction fit thatprevents shifting of second fastener 350 once secured. In one example,head 380 may also include a surface treatment or similar surface etchingthat engages and/or interacts with bottom surface 319 of set screw 314.When properly installed, the entire head 330 and a portion of shaft 320of first fastener 310 and/or shaft 370 of second fastener 350 arepositioned and reside outside the bone(s) in which first fastener 310and second fastener 350 are inserted. By positioning head 330 outsidethe vertebrae, bone fixation system 300 is configured to aid in thefusion of multi-levels of vertebrae. For example, head 330 positionedoutside the vertebrae allows for a wider range of angular relationshipbetween first fastener 310 and second fastener 350 for fastening toadjacent vertebrae or vertebrae spaced farther up or down the spine fromeach other.

Prior to insertion of second fastener 350 through first fastener 310 andinto a second desired bone, an angle guide may be used to select theappropriate angle of second fastener 350 with respect to first fastener310. FIGS. 20-22D illustrate one embodiment of an angle guide that maybe used in system 300. As illustrated in FIGS. 22A-22D, angle guide 392may include a hollow elongated shaft 393 having a first end 394, asecond end 395, a handle portion 396 proximate second end 395 and a head398 at first end 394. Head 398 includes an exterior surface 399.Exterior surface 399 may be configured, sized and shaped to engage atleast a portion of seat 344 of interior surface 336 of head 330 of firstfastener 310. As illustrated in FIG. 21 , head 398 of angle guide 392 isreceived by and inserted into passageway 332 until exterior surface 399engages seat 344 to then allow a drill to be used to pre-drill a holeprior to insertion of second fastener 350. Exterior surface 399 mayinclude a mating bulbous configuration to seat 344, matching, in oneexample, bulbous portion of exterior surface 390 of head 380 of secondfastener 350, to allow angular positioning of angle guide 392 withinpassageway 332 of head 330. In this example, a surgeon may be able toposition angle guide 392 at a desired angle relative to longitudinalaxis 334 of head 330.

In one example, system 300 may be inserted into the spine of a patient.System 300 may be implanted by first preparing a patient's vertebrae forinsertion of the bone fixation system 300. With a patient in the proneposition, a surgeon may make an incision approximately 2 cm to midline.Next, the proper location and orientation of first or primary fastener310 is determined. Using an A/P fluoroscopy, the cephalad pedicle isidentified. A Jamshidi needle may then be placed through the softtissues so that the tip is in the middle of the cephalad pedicle. Next,the Jamshidi needle is then positioned so that a “bullseye” image isseen on A/P fluoroscopy, guaranteeing a direct trajectory into thepedicle. A K-wire is then placed through the Jamshidi approximately 1 cminto the facet boney structure. The use of a K-wire technique viaJamshidis and cannulated screws ensures correct trajectories prior toinsertion of the first and second fasteners without the need for imageguidance, thereby improving safety while decreasing cost.

Fluoroscopy is then placed into the lateral position to conform that thetrajectory is appropriate. The Jamshidi is removed and the K-wire isadvanced through the pedicle into the vertebral body. Next, over theK-wire, a “pilot” hole is created using a tap. A cannulated screw drivertool is engaged with engagement opening 324 of first fastener 310. Firstfastener 310 (with the cannulated screw driver tool) is then placed overthe K-wire and first fastener 310 is inserted or screwed into thecephalad pedicle. The K-wire is then removed and the position of firstor primary fastener 310 is confirmed with lateral fluoroscopy. Afterfirst fastener 310 is properly located, the cannulated screw driver toolis removed.

Next, the area is prepared for insertion of second or secondary fastener350. First, head 398 of angle guide 392 is inserted into passageway 330of head 330 of first fastener 310. A Jamshidi needle is then placedthrough angle guide 392. Using lateral fluoroscopy, the proper andappropriate trajectory for second fastener 350 to intersect the caudalpedicle is determined. When the proper location is determined, thesurgeon gently taps the Jamshidi needle into the bone to secure theappropriate position. Next, a K-wire is placed through the Jamshidineedle and the trajectory is confirmed though lateral and A/PFluoroscopy. Under lateral fluoroscopy, the K-wire is advanced into thecaudal pedicle, and the Jamshidi needle and angle guide 392 are removed.After angle guide 392 is removed, a pilot hole is drilled using acannulated drill bit over the K-wire. Them, a surgeon will confirmposition on lateral and A/P Fluoroscopy before removing the K-wire.

Next, a cannulated screw driver tool engages tool engagement opening 383of second fastener 350. Second fastener 350 is then advanced over theK-wire to the desired depth until head 380 fully seats onto seat 344formed in interior surface 336 of passageway 332 of head 330 of firstfastener 310. The placement of second fastener 350 is then verifiedusing lateral fluoroscopy. Next, a surgeon uses a cannulated screwdriver tool to engage tool engagement opening 316 of set screw 314. Setscrew 314 (with the cannulated screw driver tool) is placed over thesame K-wire and inserted or screwed into head 330 of first fastener 310until bottom surface 319 of set screw 314 contacts head 380 of firstfastener 310 and secures head 380 against seat 344. Next, the finalplacement of system 300 is confirmed using A/P and lateral fluoroscopyand then the K-wire is removed. Finally, the patient's incision may beclosed.

In the system 300 illustrated in FIGS. 19-19D, second fastener 350 maybe of fixed orientation or be orientated in various angles relative tofirst fastener 110 depending on the designed embodiment. The specificangle configuration of second fastener 350 relative to first fastener310 is locked into place by set screw 314 within passageway 332. In oneexample, system 300 may have the ability to angulate second fastener 350approximately twelve degrees in any direction on spherical or bulboushead 380 relative to axis 334 of first fastener 310 that is necessarywhen a Jamshidi needle or K-wire is inserted through second fastener350. Without a needle or K-wire insert through second fastener 350,system 300 may have the ability to angulate second fastener 350 up toapproximately forty degrees relative to axis 334 of first fastener 310.In one example, the angle configuration of longitudinal axis 321 offirst fastener 310 relative to longitudinal axis 362 of second fastener350 ranges between approximately thirty-three degrees to approximatelysixty-seven degrees. In another example, when longitudinal axis 362 ofsecond fastener 350 is aligned with axis 334 of head 340, the anglebetween longitudinal axis 321 of first fastener 310 relative tolongitudinal axis 362 of second fastener 350 is approximately fiftydegrees.

Another embodiment of a bone fixation system 400 is shown in FIGS.23-30D. Bone fixation system 400 may include a first fastener 410 foranchoring into, for example, a first vertebrae, a second fastener 450for anchoring into, for example, a second vertebrae, a head 430, aspacer 402 and a set screw or locking cap 412.

As shown in FIGS. 27A-27D, first fastener 410 may include a shaft 420, ahead 425 and a longitudinal axis 421. Shaft 420 may include a neck 414connecting shaft 420 to the head 425. Shaft 420 includes an outersurface 414. Shaft 420 may include one or more bone engagementmechanisms 422 on at least a portion of outer surface 414 to facilitatea gripping engagement of first bone anchor to bone. In one exampleillustrated in FIG. 27A, shaft 420 may be, for example, threaded alongits entire length, threaded along only a portion of the length, ornon-threaded. In the illustrated embodiment, the external thread is asingle lead thread that extend from a distal tip of the shaft to theproximal head portion. Other suitable bone engagement mechanisms mayinclude, but are not limited to, one or more annular ridges, multiplethreads, dual lead threads, variable pitched threads, longitudinalsplines or other geometries, and/or any conventional bone engagementmechanism. Head 425 may include a top surface 426 and a side portion427. Top surface 426 may include a tool engagement opening extendinginto head 424. Side portion 427 of head 425 may include an exteriorsurface shaped like, for example, a polyaxial screw head in the form of,for example, a bulbous head, hemispherical, or partially spherical head.

As illustrated in FIGS. 28A-28C, second fastener 450 may include aproximal end 464, a distal end 466, a shaft 470, and a head 480. Shaft470 may include one or more bone engagement mechanisms 472 to facilitatea gripping engagement of second fastener to bone. Shaft 470 may be, forexample, threaded along its entire length, threaded along only a portionof the length, or non-threaded. In the illustrated embodiment, theexternal thread is a single lead thread that extend from a distal tip ofthe shaft to the proximal head portion. Other suitable bone engagementmechanisms may include, but are not limited to, one or more annularridges, multiple threads, dual lead threads, variable pitched threads,longitudinal splines or other geometries, and/or any conventional boneengagement mechanism.

As illustrated in FIGS. 26A-26D, head 430 includes a cylindrical body431. In one embodiment, the diameter of body 431 is greater than thediameter of shaft 420 extending to outer surface 414. Head 430 mayinclude a top end 432, a bottom end 434, a base 436 extending frombottom end 434, and a first arm 438 and a second arm 440 extendingupward from base 436 to top end 432. As illustrated in FIG. 26A, head430 may form receiving portions for receiving both first fastener 410and second fastener 450. Head 430 may define a first passageway 442along axis 444 for receiving first fastener 410 and a second passageway446 along axis 448 for receiving second fastener 450. In one example,axis 444 of first passageway 442 may be perpendicular to axis 448 ofsecond passageway 436. In one example, first passageway 442 may beformed as a through hole extending from first end 432 to second end 434.In one embodiment, first end 432 and second end 434 extend beyond outersurface 414 of shaft 420. Second passageway 446 may be formed as aU-shaped slot or other suitable opening for receiving second fastener450 and retaining, at least, a portion of head 480 of second fastener450.

In one example shown in FIG. 26D, U-shaped slot of a second passageway446 includes a U-shaped interior surface 433 formed by the innersurfaces of first arm 438 and second arm 440 and a top surface 438 ofbase 436. This U-shaped slot may be sized and configured to receive head480 of second fastener 450. Interior surface 433 may include, forexample, a threaded portion 431 that extends along at least a portion ofinterior surface 433 from first end 432. Interior surface 433 may alsoinclude, for example, a non-threaded portion 437 that extends along atleast a portion of interior surface 433 from first end threaded portion431 to and including top surface 438 of base 436.

As illustrated in FIG. 26D, passageway 442 may also include a seat 449that may extend along at least another portion of interior surface 433within base 436 towards second end 434. In one example, seat 449 may beshaped to correspond and mate with the shape of a portion of outersurface 427 of head 425 of first fastener 410. Exterior surface 427 maybe shaped to lie in or mate with seat 449 formed in interior surface ofpassageway 442 near second end 434. Seat 449 preferably has a shape thatmatches the shape of the exterior surface 427 and allows, for example,pivoting, spinning and rotation of first fastener 410 relative to axis444. This configuration allows a range of motion along several differentaxes, e.g. multi-directional movement or rotation, of first fastener 410relative to longitudinal axis 444. In this embodiment, the angulationachieved by system 400 with respect to second fastener 450 relative tofirst fastener 410 may be similar to that achieved by the exampleprovided for system 300.

As illustrated in FIGS. 30A-30D, set screw or locking cap 412 mayinclude a top surface 413, side surface 414 and a bottom surface 415.Set screw 412 may also include a tool engagement opening 416 extendinginto set screw 412 from top surface 213 toward bottom surface 415. Inaddition, set screw 412 may include threads 417 on side surface 414extending, for example, from top surface 413 to bottom surface 415, oralong a portion thereof. Bottom surface 415 may be sized and shaped toengage at least a portion of the side surface of head 480 of secondfastener 450. Threads 417 are sized and configured to engage threadedportion 431 that extends along at least a portion of interior surface433 from first end 432 of head 430.

As illustrated in FIGS. 29A-29D, spacer 402 includes a top surface 403,a bottom surface 404 and a side surface 405. Spacer 402 is sized andconfigured to be disposed between top surface 426 of first fastener 410and the side surface of head 480 of second fastener 450.

The system 400 may be implanted by first preparing a patient's vertebraefor insertion of the bone fixation system 400. Next, a surgeon obtains afirst fastener 410 and head 430. First fastener 410 is inserted throughfirst passageway 442 until head 425 of first fastener 410 engages seat449 within base 436 of head 430. First fastener 410 is then insertedinto bone in a selected direction and orientation. Next, spacer 402 ispositioned onto of top surface 426 of first fastener 410. Then, secondfastener 450 is inserted through second passageway 446 and positionedinto bone in a selected direction and orientation relative to firstfastener 410. Second fastener 450 is locked into place by set screw 412.Head 480 of second fastener 450 is locked between bottom surface 415 ofset screw 412 and top surface 403 of spacer 402 as set screw 412 isscrewed into passageway 442. As set screw 412 is screwed down onto theside surface of head 480, first fastener 410 is also being set intoplace through the force translated through the contact of spacer 402with the side surface of head 480 of second fastener 450 and top surface426. In the system 400 illustrated in FIGS. 23-30D, first fastener 410may be orientated in various angles relative to second fastener 450. Thespecific angle configuration of first fastener 410 relative to secondfastener 450 is locked into place set screw 412 within passageway head430.

Similar to the prior embodiments, a drill guide may be used to pre-drillholes in the bone for both first fastener 410 and second fastener 450.Alternative constructions and configurations of a drill guide may alsobe used in accordance with the principles of the present invention.

In each of the embodiments described herein, first and second fasteners,drill guides and other components may include through holes toaccommodate, for example, K-wires, drills and Jamshidi needles to assistwith positioning and orientation during surgery. For example, firstfastener 110 and second fastener 150 include through holes along theirlongitudinal axis to accommodate, for example, K-wires. In addition,alternative methods may be employed to install the various systemsdescribed herein. For example, a surgical robot or an image guidancesystem may be used to perform or aid in performing all or portions ofthe various steps required to properly install a system constructed inaccordance with one or more aspects within a patient.

Although the fasteners shown and described through the presentdescription, such as fasteners 110, 210, 310 and 410 and 150, 250, 350and 450 are shown as being straight, it is also contemplated that one ormore of these fasteners may have curved shafts that may be driven intothe patient's vertebrae rather than screwed, or the shafts of thesefasteners may also be slightly curved.

As may be recognized by those of ordinary skill in the art based on theteachings herein, numerous changes and modifications may be made to theabove-described and other embodiments of the present invention withoutdeparting from the scope of the invention. The fasteners, elongatemembers, and other components of the devices and/or systems as disclosedin the specification, including the accompanying abstract and drawings,may be replaced by alternative component(s) or feature(s), such as thosedisclosed in another embodiment, which serve the same, equivalent orsimilar purpose as known by those skilled in the art to achieve thesame, equivalent or similar results by such alternative component(s) orfeature(s) to provide a similar function for the intended purpose. Inaddition, the devices and systems may include more or fewer componentsor features than the embodiments as described and illustrated herein.For example, the components and features of FIGS. 1-30D may all be usedinterchangeably and in alternative combinations as would be modified oraltered by one of skill in the art. Accordingly, this detaileddescription of the currently-preferred embodiments is to be taken asillustrative, as opposed to limiting the invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise” (andany form of comprise, such as “comprises” and “comprising”), “have” (andany form of have, such as “has”, and “having”), “include” (and any formof include, such as “includes” and “including”), and “contain” (and anyform of contain, such as “contains” and “containing”) are open-endedlinking verbs. As a result, a method or device that “comprises,” “has,”“includes,” or “contains” one or more steps or elements possesses thoseone or more steps or elements, but is not limited to possessing onlythose one or more steps or elements. Likewise, a step of a method or anelement of a device that “comprises,” “has,” “includes,” or “contains”one or more features possesses those one or more features, but is notlimited to possessing only those one or more features. Furthermore, adevice or structure that is configured in a certain way is configured inat least that way, but may also be configured in ways that are notlisted.

The invention has been described with reference to the preferredembodiments. It will be understood that the architectural andoperational embodiments described herein are exemplary of a plurality ofpossible arrangements to provide the same general features,characteristics, and general system operation. Modifications andalterations will occur to others upon a reading and understanding of thepreceding detailed description. It is intended that the invention beconstrued as including all such modifications and alterations.

The invention claimed is:
 1. A bone fixation device, comprising: athreaded shaft for engaging bone tissue, the threaded shaft defining acannula configured to receive a guide wire, the cannula extending alonga first axis; and an enlarged head extending from a proximal portion ofthe threaded shaft, the enlarged head comprising: a tool engagementopening in communication with the cannula, the tool engagement openingoriented along the first axis and comprising an interior surfaceconfigured to receive a tool to rotate the threaded shaft about thefirst axis into bone tissue; and a passageway configured to receive amulti-axial bone fastener, wherein the passageway is oriented along asecond axis oblique to the first axis, and wherein the passagewaycomprises an interior surface between a first opening and a secondopening, the interior surface defining: a seat configured to engage ahead of the multi-axial bone fastener; and a threaded portion configuredto engage a set screw along the second axis toward the second opening tocontact the head of the multi-axial bone fastener.
 2. The bone fixationdevice of claim 1, wherein the seat comprises a concave-shaped surfaceconfigured to receive a convex rounded portion of the head of themulti-axial bone fastener, and wherein the passageway is sized andshaped to allow partial rotation of the multi-axial bone fastener aboutat least two axes.
 3. The bone fixation device of claim 1, wherein toolengagement opening is configured to receive a hex screwdriver feature.4. The bone fixation device of claim 1, wherein the cannula is incommunication with the passageway via the tool engagement opening. 5.The bone fixation device of claim 1, wherein the enlarged head comprisesa proximal surface oriented obliquely to the first axis.
 6. The bonefixation device of claim 5, wherein the first opening comprises acircular opening through the proximal surface, and wherein the firstopening is offset to provide clearance to access the tool engagementopening.
 7. The bone fixation device of claim 5, wherein a proximalportion of the threaded shaft includes a tapering portion that tapersradially inward from, and extending along, the first axis from aproximal portion of the tapering portion towards a threaded portion ofthe threaded shaft.
 8. The bone fixation device of claim 1, wherein thetool engagement opening extends through the threaded portion of thepassageway.
 9. The bone fixation device of claim 1, wherein the threadedportion of the passageway extends to a concave-shaped surface to allowthe set screw to contact the head of the multi-axial bone fastener. 10.A bone fixation system, comprising: a first bone fastener comprising abulbous head and a first threaded shaft; a set screw; and a second bonefastener, comprising: a second threaded shaft extending along a firstaxis; and a head extending from a proximal portion of the secondthreaded shaft, the head comprising: a tool engagement featureconfigured to receive a driving tool to drive the second threaded shaftabout the first axis into bone tissue; and a passageway configured toreceive the first bone fastener, wherein the passageway is orientedalong a second axis oblique to the first axis, and wherein thepassageway comprises an interior surface between a first opening and asecond opening, the interior surface defining: a distal portionconfigured to engage the bulbous head of the first bone fastener in amulti-axial relationship; and a threaded portion configured to guide theset screw along the second axis toward the second opening to contact thebulbous head of the first bone fastener.
 11. The bone fixation system ofclaim 10, wherein the set screw is configured to fix the orientation ofthe bulbous head of the first bone fastener against the distal portionwithin the passageway.
 12. The bone fixation system of claim 10, whereina bottom surface of the set screw includes a concave portion configuredto engage the bulbous head of the first bone fastener.
 13. The bonefixation system of claim 12, wherein the bottom surface of the set screwoperably engages an outer surface of the bulbous head of the first bonefastener.
 14. The bone fixation system of claim 12, wherein the bottomsurface of the set screw comprises a treated surface configured toprovide a friction fit with the bulbous head of the first bone fastener.15. The bone fixation system of claim 10, wherein the second threadedshaft of the second bone fastener includes a first cross-sectional widthand the head of the second bone fastener includes a secondcross-sectional width, wherein the second cross-sectional width isgreater than the first cross-sectional width.
 16. The bone fixationsystem of claim 10, wherein the head of the second bone fastenercomprises a body having an arcuate surface, and wherein the threadedportion of the head comprises threads around an entire innercircumference of the body.
 17. The bone fixation system of claim 10,wherein the tool engagement feature is accessible through the passagewayof the head of said first bone fastener.
 18. The bone fixation system ofclaim 17, wherein the tool engagement feature comprises an openingconfigured to receive a tool for anchoring the second bone fastener intobone tissue.
 19. The bone fixation system of claim 10, wherein thesecond bone fastener is cannulated.
 20. The bone fixation system ofclaim 10, further comprising a guide tool for facilitating placement ofthe first bone fastener into bone tissue, wherein the guide toolcomprises: a rounded head configured to be placed against the distalportion of the passageway and rotated about at least two axes; and acannulated shaft configured to receive a drilling tool to form a hole inthe bone tissue for the first bone fastener.